Well, this is a welcome surprise for those of us waiting for Ubuntu 10.04, the Lucid Lynx. Several users are reporting that their iPod Touches and iPhones (including the 3GS) work in alpha 3 - without tweaking, without jailbreaking, without patching - with Nautilus and Rythmbox.

which I did not know the answer to. If you start up your iPod with the Mac version of iTunes, he tells me that it sets the file system to HFS+. Is this true?

For non iPhone OS devices it is true. If you initialize your iPod in OS X the filesystem is HFS+, if done in Windows it is FAT32. iTunes accesses these iPod devices over a protocol similar to UMS, in contrast to the iPhone OS which it communicates with via a limited Ethernet over USB protocol, the usbmux protocol. iPhone OS devices are formatted with their own filesystem, I presume it's a variant of HFS+ though I'm not 100% sure of that.

Then, he is worried that if he puts in Windows and iTunes on it, which he anyway is not enthused about, what happens if someone updates a Mac intitialised system from a Windows version of iTunes? Does it explode?

You won't be able to do it. Windows cannot read HFS+ without third party filesystem drivers, and afaik none of these work with iTunes. The reverse is not true however, OS X can obviously read and write FAT32... but, in typical Apple fashion, they've got an arbitrary limitation that will not allow you to update Windows-formatted devices in OS X. When you try, it gives you a message that you must initialize your iPod (i.e. reformat it) for use with OS X. Stupid and pointless, since OS X is fully capable of handling FAT32 to begin with. So no, it won't explode, but you might from frustration.

Thanks, didn't realize they'd added an option in there for that. I take it the update limitation for FAT32 devices in OS X is gone too then? I haven't owned a non-iPhone OS iPod for a while, thought about getting a 5th gen Nano for portability and battery but decided on a Rockbox-ready Sansa Fuze instead for its ogg support.